Technical Field
The present invention relates to a method for controlling a feed arrangement having a wind energy installation for feeding electrical power or electrical energy into an electrical supply system. Furthermore, the present invention relates to such a feed arrangement. Furthermore, the present invention relates to a wind farm having a plurality of wind energy installations and at least one feed apparatus.
Description of the Related Art
Wind energy installations which generate electrical current from wind and feed this electrical current into an electrical supply system are generally known. An example of such a wind energy installation is illustrated schematically in FIG. 1. Such a wind energy installation can therefore also be interpreted as a feed arrangement, which comprises a wind energy installation.
Conventionally, but at least preferably, wind energy installations are or have been operated in the so-called system-parallel operating mode. This is generally understood to mean that the respective wind energy installation generates in each case as much electrical power as is possible owing to prevailing wind and feeds this electrical power into the electrical supply system. The electrical supply system, which will also synonymously be referred to as a network or system below, has compensated for or absorbed resultant fluctuations in the fed power i.e. the power that has been fed therein.
Such a system-parallel operating mode is problematic for the system with an increasing share of electrical power from wind energy installations in the system, however. It is desirable that wind energy installations also support the electrical system and can in particular adapt to the demand for power of the electrical system.
In this sense, solutions are already known in which wind energy installations can perform system-supporting functions. For example, U.S. Pat. No. 6,984,898 discloses a method in which the wind energy installation regulates its fed power depending on the system voltage. U.S. Pat. No. 6,891,281 discloses a method in which the power is regulated depending on a frequency of the voltage in the system. U.S. Pat. No. 7,462,946 describes a method for feeding electrical power into a supply system by means of a wind energy installation which can take account of a short circuit in the supply system. U.S. Pat. No. 6,965,174 proposes a method in which a wind energy installation feeding into the system adjusts a phase angle and therefore a reactive power component of the fed power depending on the system voltage in order also thus to make a contribution to the system support. U.S. Pat. No. 7,525,208 also proposes taking into account short circuits in the system.
All of these methods make a contribution to the system support, but do not resolve the fact that a wind energy installation can generate no more electrical power from the wind than the wind conditions prevailing in each case permit. To this extent, in particular an increase in power in respect of amplitude and also the temporal duration of such an increase are subject to narrow limits.
In order to be able to also achieve an increase in the fed power of a wind energy installation, EP 2 411 669 proposes achieving a short-term increase in power for supporting the network by virtue of the fact that power from the centrifugal mass of the rotating rotor of the wind energy installation is utilized. Such an increase in power is also subject to narrow limits which result not least from the maximum stored kinetic energy in the rotor. In addition, a certain degree of complexity is required to convert the kinetic energy of the rotor of the wind energy installation into electrical current in order to effect the desired increase in the fed electrical power.
The German Patent and Trademark Office has searched the following prior art in the priority application: DE 10 2009 018 126 A1 and DE 10 2008 052 827 A1.